A roller skate generally includes a plurality of wheels carried and supported by a lower frame portion attached to a roller skate upper shoe or boot. The upper shoe portion provides the support for a skater's foot while the lower frame portion provides the rigid substructure or undercarriage for the roller skate's wheels. Roller skates are very maneuverable and capable of moving at a higher speed as compared to conventional skates.
In prior art design, the conventional upper shoe portion of a roller skate is usually made of rigid, non-ventilating, and plastic material with an inner liner. The plastic material provides the rigid outer structure of the upper shoe portion and the soft inner liner made of sponge rubber or other sir Dial offers some comfort to the user. To ensure lateral stability, conventional alpine ski-boot designs have readily been adapted to roller skates. These boots provide support and durability necessary for roller skates.
However, the above prior art has an important drawback in that, generally, the size of the roller skate is fixed. Many users of the roller skate are children whose feet grow rapidly with their ages. A suitable size for a child of, for example) ten years old will become probably too small when the child tuns into eleven years old. Because roller skates are quite expensive, the cost of them may be a significant burden to parents. Although some of the skates are manufactured with adjustable size, the adjustable braces and supports for accommodating numerous shoe sizes and shapes are usually bulky and uncomfortable. There is a strong demand for a roller skate which is comfortable to wear and whose size is easy to adjust